Continuous geodetic time-transfer analysis methods

Area of Science:

• Geodesy
• Satellite Navigation Systems
• Metrology

Background:

• Carrier phase measurements from Global Positioning System (GPS) are crucial for precise time and frequency transfer.
• Existing methods face limitations due to inconsistencies between code and phase observations and data discontinuities at daily boundaries.

Purpose of the Study:

• To identify and mitigate issues affecting the quality of time and frequency transfer using GPS carrier phase measurements.
• To develop and implement strategies for overcoming code-phase inconsistencies and daily data gaps.

Main Methods:

• Classification and detection of events causing time-code inconsistencies, with implementation in Bernese GPS Software.
• Development and testing of two new methods, clock handover and ambiguity stacking, to address daily discontinuities.
• Comparison of new methods with an independent time-transfer technique using network station data.

Main Results:

• Strategies implemented can detect time-code inconsistencies exceeding the 20 ns noise level.
• Both clock handover and ambiguity stacking methods enhance transfer stability for averaging times shorter than 8 days.
• Continuous solutions demonstrate robustness against modeling and preprocessing errors, preventing permanent bias accumulation.

Conclusions:

• The developed methods effectively address key limitations in GPS-based time and frequency transfer.
• Short-term stability is improved, while long-term benefits require further investigation.
• Continuous processing solutions offer reliable and bias-free results for high-precision applications.